In power application, high-speed, low-loss diodes are often desired, e.g. as clamp and anti-parallel diodes. Further, these diodes are often desired to block high voltage in the reverse direction, have low resistance in the forward direction (Ron), and/or have a high robustness. The Schottky diode, which is a majority carrier device and avoids any switching delays associated with minority carrier recombination, is a very fast diode. Schottky diodes can also have a low turn-on voltage, but may have an increased leakage current and low breakdown in the reverse direction compared to bipolar (p/n junction) diodes.
To combine the speed of the Schottky diode and the blocking capability of the bipolar diode, the merged PiN Schottky (MPS) diode, also referred to as Junction Barrier Schottky (JBS) diode, was developed. The MPS diode may include a drift layer and alternating Schottky areas and shielding regions forming respective pn-junctions with the drift layer. In forward direction (of the pn-junctions), the MPS diode may function similar to a Schottky diode in that majority carriers are injected across a Schottky-junction (Schottky contacts) formed by a metal-semiconductor interface in the Schottky areas. This may result in low turn-on voltage and fast switching. In the reverse direction (in which the pn-junctions are reversely biased), depletion regions may be formed at the pn-junctions so that the Schottky-junctions are shielded against highest electric fields. Accordingly, high leakage current arising from the Schottky junctions can be significantly reduced.
However, there is a need to further improve turn-on voltage and/or robustness of MPS-diodes without substantially deteriorating other device parameters.